# How to comparison decimal numbers

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Thar on 1 Dec 2015
Commented: Walter Roberson on 2 Dec 2015
Hi all!
I have two matrices. They have one column. First matrix is:
7.551119
7.551154
7.551189
7.551224
Second matrix is:
7.551111
7.551146
7.551181
7.551215
I want to comparison two columns but only 5 decimal places. I don't like round my numbers like:
7.55112
7.55115
and so on, if I use the function round.
##### 2 CommentsShowHide 1 older comment
Thar on 2 Dec 2015
I want to keep the 5 decimal points, but not rounded the numbers. for example for the number 7.551187 i want to keep only the 7.55118 and not round to 7.55119.

arich82 on 2 Dec 2015
You can truncate (without rounding) using floor (or fix, if your numbers can be negative):
x = [ ...
7.551119; ...
7.551154; ...
7.551189; ...
7.551224; ...
];
y = fix(x*1e5)/1e5;
output:
y =
7.551110000000000
7.551150000000000
7.551180000000000
7.551220000000000
Thar on 2 Dec 2015
Thank you!!

Image Analyst on 2 Dec 2015
You need to use a tolerance. See the FAQ for a complete explanation: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

Thorsten on 2 Dec 2015
Edited: Thorsten on 2 Dec 2015
You can round to 5 decimal places using
xr = round(x*1e5)/1e5;
You may want to set
format long
such that the result is properly displayed.
Walter Roberson on 2 Dec 2015
To check, Thodoris, you are okay with 7.551111 comparing equal to 7.551119, but 7.551119 should not compare equal to 7.551121 even though that is closer to it than 7.551111 is?